A growing shortage of organic fuels and increasing awareness of the environmental hazards caused by their use in motor vehicles has made desirable the use of electrically powered vehicles. Due to an inability of the state of the art to produce a sufficient amount of power for vehicular propulsion from batteries, vehicles employing such power sources are generally of lightweight construction while the batteries are relatively large and heavy. The inertia of the batteries is often sufficient to place severe mechanical stresses on the vehicle chassis, capable of upsetting the vehicle or causing structural damage to it, when the vehicle is linearly or angularly accelerated or decelerated.
Lightweight vehicles of the type heretofore discussed often employ belt or chain drive power transmissions to transmit power from a motor to one or more of the vehicle's wheels. In such belt drive systems, either the motor shaft or transmission pulley or sprocket is movable, the belt being tensioned by spreading the pulleys or sprockets apart and frictionally locking them in place. The tension of the belt or chain tends to force the pulleys or sprockets toward one another thereby loosening the belt or chain. Relatively frequent adjustment is required in order to maintain adequate belt tension. It is therefore desirable to utilize the weight of the battery to tension the drive belt or chain.